Communication system



w. M. BACON ET A1. 2,358,375

COMMUNICATION SYSTEM Filed Aug. 2e. 1942 e sheets-sheet 1 Sept. 19, 1.

Sept. 1944. M BACON ET AL COMMUNICATION SYSTEM Filed Aug. 2e, 1942 e sheetssheet 2 R/ZED I POL AR/ZED POLAIZID ATTORNEY w. M. BACON E1- AL 2,358,375

Sept. 19, 1944.

COMMUNICATION SYSTEM y e sheets-sheet Filed Aug. 26. 1942 @fw/M@ gif-LW l ATTORNEY Sept. 19, 1944. w. AM. BACON ETAL COMMUNICATION SYSTEM Filed Aug. 26, 1942 6 Sheets-Sheet 4 COMMUNICATION SYSTEM Filed Aug. 26. 1942 6 Sheets-Sheet 5 mllullnlll."

hx Y Fut .ai Wks mi? Nut ,D E y C m M. vlA T NDDM.. A OMMA CKKm ANWsvf. /KM K sw. E s m R S m w m w DVD. Nb, .065K \ON Patented Sept. 19, 1944 CO-MlVIUNIGATION SYSTEM Walter M. Bacon, New York, N. Y., and Fullerton S. Kinkead, deceased, late of New York, N. Y., by Rita. Smith Kinkead, administratri'x, New York, N. Y., assignors to Bell Telephone vLahoratories, Incorporated, New York, N. Y., a cor poration of New York Application August 26, 1942, Serial No. 456,147

Claims.

This invention relates toan improved telegraph subscribers station, arrangements and control equipment suitable for connection to and operable in combination with comprehensive telegraph transmission system and in one embodiment thereof in combination with comprehensive telegraph network employing -automatic switching apparatus.

An object of this invention is to provide a more flexible outlying station or subscribers equipment and apparatus and control equipment therefor for more efficiently and effectively receiving messages from said outlying station and equipment.

Telegraph systems employing a storage or tape control transmitter for the transmission of message material over a transmission system to another stationr 'are frequently" arranged so that when the tape passes out of the transmitter or when the supply of message material available for transmission is reduced below a predetermined quantity, the operation of the transmitting apparatus is interrupted and frequently disconnected from the transmission channel or system in order to permit the channel to be employed for transmission from another transmitter or other outlying station or equipment.

' 'It sometimes happens that there may be more than one source of message material at one or more of the outlying stations, each of which will produce a punched tape or stored message material available for transmission.

In accordance with this invention the circuits at the subscribers station arerarranged so that the attendant thereat will have a short interval of time of approximately thirty seconds in which to insert a second or succeeding tape or group of stored signals after the first group has passed out of the transmitter before the transmission path to the transmitter in question'is interrupted.

. Thus the transmitter in question is permitted to transmit from a plurality of tapes, one after another, provided they are inserted in the transmit- Vter within a predetermined interval of time after the previous one passes out of the transmitter. In the specific embodiment of the invention Vdescribed. herein, the apparatus at the subscribers station, in accordance with this invention,

' has been arranged to cooperate with the switching system disclosedin copending application of Branson et al., Serial No. 448,878, filed June 27,

' 1942, the Ydisclosure of which application is incorporated herein by reference to the same extent as if wholly included herein.

s In the specific embodiment'of the invention disclosed herein, one of the outlying subscribers station circuits or equipment, as disclosed in said Branson et al. application, has been modified in accordance with this invention iinorderrto permit the .attendant or subscriber thereat to insert a plurality of tapes in a tape control transmitter, one after Vthe other, Without losing its turn of transmission provided .the succeeding tape `is inserted in the .transmitter within a predetermined maximum interval .of timeafter the Aprevious tape has runout of the machine.

It will .be readily appreciated .by thosexskilled in the art that modification in `accordance `with this inventionmay vbe employed at any of thestations in combination with any of ,the transmitters Vlocated thereat. Y

The foregoing Vobjects .and features of this invention maybemore .readily understood from the following description whenv read with reference tothe attached drawings, in which:

Fig. 1 illustrates a lmanner in which Figs. 2

' through 7 are positioned adjacent each other;

Figs. 2 through 7, `when positioned -inaccordance with Fig. 1illustrategdetailsiof the present invention in'an embodiment suitable for use in combination with the switching system described in said above-identied application `of Branson et al. Y

Specifically, Figs. v2,;3 ,and fl show details of a subscribers station equipment andl control equipment associated therewith; whileFigs. 5, ,fa'nd 7 showrinschematic form thevarious circuits and apparatus and theirmanners of {cooperationin VaV typical switching system such as described inl said with which the improved station equipment and V.control apparatus in accordance with this inventiony arearranged to cooperate.

4Figs.,3 and 4 of this application are similar to Figs. 11 and 24 of said Branson et al. application and maybe directly substitutedforthese,figures l providing that the .associated ,additional equipment shownY in detail on the right-hand portion of .Fig.`2y isalso includedwith Figs. -3 and f4 of .A this application. ,With this addition Figs. 3r and Afl ofthe present applicationr may be .substituted fory the corresponding' Afigures in lsaid Branson application .without Vfurtl'ierv change. Injthiscase, however, .the equipment .andl apparatus shown in Figs.`3 and 4'as` Well vasthe right-hand portion of Fig. 2 will operate as described lflere'in".`

The remaining portion of Fig. 2vas well asjFigs. 5, Gand 7 show in outline form'thejvarious circuits ,andiapparatus comprising a typical switching system., such as Vset forthjin the. above-identied Branson et al. application.

qhalf duplex party line.

It is to be understood that the apparatus and circuits in accordance with the present invention for controlling a transmitter may be applied to any of the transmitters of the other stations or other transmitters incorporated in the system including transmitters located either at other stations served by the same party line or by sta, tions served by different party lines. As will be appreciated by those skilled in the art, the transmitters may be controlled Iby any of the secondary switching centers and any of the centers may control one or more transmitters. In each case, where desired, an arrangement in accordance with the invention may be provided.

Before describing the operation of the improved control arrangement in accordance with this invention, reference should be made to the other equipment of the system which is de` scribed in detail in the above-identified Branson et al. application.

Briefly, the system comprises a plurality of party lines and 560. These party lines comprise a receiving channel 202 and 56|, respectively, for the transmission of signals from a central switching center shown in Figs. 6 and '1 to the respective stations served by these party lines. The party lines also include the transmission channel 203 and 562, respectively, for the transmission of signals from the outlying stations to the central switching center. As described in the above-identified application of Branson et al.,

these party lines may be arranged to operateV either on a full duplex or half duplex basis. The

party line 20| is assumed to be a full duplex party line, while the line 560 is assumed to be a As will be well understood by those skilled in the art, any number of full duplex and half duplexlines may be provided. As shown in the drawings, full duplex party line 20|-extends tothe secondary switching centers 215, 3|4 and 5|3.

These switching centers-control the stations 216,211, 218 and 4|9 and Vthe receiving reperforator 4|.0 and stations tions 566 through 514, inclusive.

Lines 590 represent a line extending from the switching center shown in Figs. 6 and '1 to a vsecond switching center 593. This line orV trunkV includes a channel 59| for transmitting messagesfrom the switching center shown in Figs. 6 and 7 to the second switching center 593 where receiving equipment 594 is associated therewith. The trunk 590 also includes a second channel for transmission of signals from the sending equipment 595 at the second switching center 593 to Ythe central exchange shown in Figs. 6

and 7.

The party lines 20| and 560 as well as the trunk circuit 590 may include any suitable type of telegraph transmission channel. the drawings, these lines are shown as two oneway full metallic transmission paths in an effort to avoid iurther complication of the disclosure. It is to be understood, however, that' these transmission paths may include one or more of the following types of telegraphV transmission systems and in actual practice willV usually combine the number of the different iiollowingV types of transmission paths, as will be readily understood `by thoseV skilled in the'art. paths of the different lines will vary'fromsection to section independently of the type of trans- 75 TheA transmission `These channels may also include channels of the so-called time division multiplex telegraph systems Yfor the transmission of signals in either one or both directions.

The telegraph transmission channels may also include channels of voice frequency carrier telegraph systems as well as channels of high frequency carrier current telegraph systems and also radio channels.

These party lines may also include the usual types of terminal and interconnecting equipmenty for the various types of communication systems employed as well as4 the usual types of ampliners, repeaters, volume compensators and other control equipment generally employed with systemsV of the respective types. Inasmuch as the respective types of telegraph systems operate in their usual manner and are well understood by those skilled in the art, they have not been shown in the drawings but merely represented by two one-way telegraph channels for each of the lines of the system.

As set forth in the above-identified Branson et al. application, the party lines terminate at the central exchange in equipment individual to As shown in each of the lines. The incoming channel party line 20| terminates in an incoming line circuit 622. The incoming line circuit causes the message to be recorded either `by receiving-only teletypewriter 623when the messages are intended for the central switching station, or upon a combined reperforator and transmitter 624 comprising reperforating unit 626 and a transmitting unit 625. The transmitter 625 is associated with the director circuit 621 which controls crossbar switch including the selector magnet 628 and the holding magnets and causes the transmitter to be connected to some channel extending towards the party line for which the message is intended.

Each message is preceded by a plurality of address characters, which characters control the directing circuit 621 andcause transmitter 625 to be connected to the proper line under control of these address characters. Each of the outgoing lines is provided with one gr more channels of transmission through the crossbar switch. The party line 20| is provided with two sets of channels and each channel is provided with a group of relays individual thereto illustrated symbolically at 620 and 62|. Each of the channels is also provided with a combined reperforating and transmitting instrument 6|4, 6|5. The transmitting units of these instruments are arranged to transmit alternately'over the receiving channel of the party line 20|. 'I'hey are provided with Various control relays 6| I, 6|2 and The transmitter start circuit 6|6 is also associated with the receiving channel or party line 20| for transmitting transmitter start signals or control patterns over this channel. These transmitter start patterns control the switching equipment'at the secondary switching center and cause the associated transmitters to be started '=2,'3,58,37-5 into operation when itheylare supplied with 'instruments at the 'interconnecting station; this -s'tored -message material `available for f transmisbsion. Y i f Y. 'The secondary!switching` centers also respond tolat least certain of.v the address characters and ,f cause the receiving equipment controlledby them Ato be selectively AVand` operatively connected -to the -`receiving channel vof the party line 'in accordance with address characters so that they will receive the 'messages intended forthem.

The-other party lines of the trunk circuitslare 'similarly equipped with lthe various circuits as -describedabove.Y Inthecaseof theY half duplex `lines only onechannel -through the crossbar switch will generally be provided-since half duplex Vlines will only be yprovided when trailic or Umessages -forthe stations and vline connected --Ltheretoareenot heavy;n No transmitter start circuit has been'shown' for thetrunk circuit because l'such a circuit --generally will be unnecesvrsair'ysincethere will-be no transmitters to be 'startedunder control Aof the-central switching center. l'provided for each of -the Ylines and trunks opera-te'in-substantially-the'same manner and perform" substantially -the same function.

With these exceptions the equipment Message originating equipment comprising --monitoring teletypewriters 1|0, keyboard perfo- 'rator 1li, transmitters 1-l2, control relays 1I3 and a director circuit`1I-4 is provided at the central switching station'for the transmission ofV tmessages from vthat station to any of the other :stations of the system.

Inv addition a vmiscellaneous intercepting circuit 121, receivingreperiorators 126 andl tape receptacle 125 are Yprovided for the reception of improperly addressed messages and'other messages which Vfail to properly control the switch- A wilful intercept circuit 124 anda combined lreperforator and transmitter 120 comprising a .reperforator unit-,12| and -a transmitting Vunit 122 together with a,v director circuit 123 are pro- 'Y vided for the `receptioncf certain messages in- `tended forI stations-which it isgdesired for one `Vvreason-or another to intercept and prevent-from transmissior'i to their ultimate station of destination at the particular moment.

` f The operation of Vvthe circuits vof sucha typical switching system has beendescribed in detail the above-identified Branson et al. application Y)and need not be repeated here; It is to be `underlstood, however, that equipment and lcircuits of lthis invention cooperate with circuits ofsaid ABranson et al.V application as will be 'describedi hereinafter.

1 In large switching systems of this type it frequently happens that it is desired to transmit 4tape would use Aup the entire .turn-ofthat'sta'- tionV for transmitting over the comprehensive ment-which permits a secondtape to be inserted in a-transmitter at the transfer station a short interval kof time after .a previous tape passes out of the transmitter without causing "the rdisconnection of the transmitter from theparty line land thus without causing the transmitter tok lose its turn for-transmission.

If; the Asucceeding tape is not insertediin the 4transmitter within a predetermined-short intervval of time, the transmitter will be disconnected from the system and another transmitter started' asset forth in the above-identiiiedapplication of Branson et al. v 1

Brieiiy. the circuits at the secondary switching point 3M' are shown intheir normal condition with relay 311 maintained in the position Ivsome of the -messages over Vothersystems of the l sametype or over other types of Vsystems or other circuits noti forming a part of the main switch- "ing:system.

Atthe stations at which the messages are transferred `from one system vto another there will usually be severalsources of signals, that is,

several-different instruments forgperforating the tape'in -accordance with the messages to be transmitted over the large switchingsystem in ques-- tion. In the systemjset forth-in the Aabove-idenltiiie'd patent-application of Branson et' al., as soon as the tape runsout'oi any one of the trans- :mitters of' the system, that'transmitter loses its Yturn to transmit andibecomes disconnectedgfromr the party line. j Thus," incase only a' short piece vof tape isperiorated by one ofthe perforatin'gI shown due to the eiect'of the current flowing through' its upper winding which is greater than the effect of thefcurrent flowing through its lower winding. n l v When it is desired to start a transmitter off-.a party line, theY operator at the centralstation will operate keys assooiatedwith the transmitter start circuit SIB andY causea start pattern to-'be transmittedl over the receiving `channel 202 of party line 294. If .the transmitter start circuit is set to operate automatically, Vthe transmitter start pattern will be transmitted over the receiving channel 202 of party line 20H, either upon the cessation of the reception of signals over-the vtransmitting channel of this party line or upon the reception of the end of the transmission signalsas set forth in the application of Branson et al. Y,

in progress att'he'time the operation of this circuit is initiated. After a short] pause a blank signal combination is transmitted by the-transmitter start circuit. After-another short pause a line-feed signal combination is transmitted` and this in turn is' follow'ed'bya selecting code combination which is assigned to one of the transmitters served by the party line. After the transmissionof this signal-the'transmitter' will start transmisison provided it is' supplied withmessage 5d materiallin theform of perforated tape'for'tr'ansmission' to some other station. 1 r l As indicated in the above-idenunad application of Branson et al., the transmitters at the Itransfer station or, in fact, any-other transmitters in the system may be assigned more than one code combination for the selection thereof so that in case of particularly vheavy traic, as will usuallybe'encountered at'fthe ltransfer. stations, the transmitters at these stations may be given moreY opportunities to transmit and thus are in position to handle' the greater amount `of q message material originating at'these stationsfor `stations of tliemain switching system.

At each ofthe secondaryr switching centers ratus in accordancewith-these signals to 'properly of` vtheparty line,' monitoringV and selecting appav ratus receives all of the signals transmitted over Y fthe receiving channelgof party line 20| andcontrols the'associated switching circuits and' appaing of relay 341. `.30 andthe manner in which itselectiyely closes ...the .respectivecontacts in response to received sig- Athrough the upper Winding of relay 311. ever, the current does not immediately cease ow- -therebytotherespective channels of the party fline.. Only the. switchingequipment atv the sec- -ondary 'switching center .g3 41 is :shown in detail :in .the drawings, but it is to be understood that vsimilar switching equipment isprovidedat each -z AtV .the secondary' switching centerv 3| 4 the Sm'onitoring selector 30| will respondto the :blank signal of the transmitter start pattern translmitted from the vtransmitter start circuit BES by causing the blank contacts BLK to momentarily(Y close. Operation of the blank contacts BLK com- -pletes a circuit for the 'operation of relay 341 ffrom battery throughthe lowerfwinding of relay 346; winding of relay 341 to ground through. the :momentarily closed contacts BLK. Current flowing through the lower winding of relay 345 causes the armature of this relay to be maintained in the position shown in the drawings.

1 The operation of relay 341 completes an obvvious circuit for the operation of relay 318. Relay 31|! inoperating completes a circuit for maintaining itself operated from battery through its winding and the break contacts of relay 319 and the fright-hand inner operated contacts of relay 318 to ground through the break contacts'of key 316., Y The operation of Vrelay 318 also extends a cir- -cuit from battery through the upper winding of rrelay 349 `and 'the right-hand Vouter operated contactsof relay 318 to ground through the mo- `mentarily closed universal contacts UN. These UN contacts close aV short interval of time after the "blank contactsBLK-close` and open a short interval of time before the blank contacts open.

The eiect produced by the :current iiowing .through the upper winding of relay 345 is not 1 as great asthe -elect Vproduced *bythe current `ilowingthrough thev lower winding of this relay. ',Consequently, the armature of this relay remains in the 4position shown in the drawings.

v Atthe end ofthe responseof the selectorV 30| Y .to the blank signal, the blank contacts BLK will open and interrupt the circuitthrough the wind- A suitable type 'of selector nals is set forth in greaterdetail vin UnitedStates Patents 2,120,235, grantedto Beattie Let' al. on 4-June 14, 1938; 2,112,234, granted tol Beattie on ,March29, 1938; and 2,154,547 granted to Walker on April 18, 1939; the disclosureslof which pat-1'.:-

-ents ,are hereby made a part ofthis application ,asitfullyincluded herein.;. t .1

.i ,Theirelease of relay 341 interrupts a circuit ing throughthis winding Ibecause the` upper ter- :minal of condenser 3,92, starts Ato vcharge to Vbattery potential `through theupper winding ofre- ;lay.31 1. The eiect of .this charging current upon,v the armature ofjrelay 311 is suiicient to overcome -gthe Aeffect of the current flowing throughthe lower Awindingfofthis relay and maintain the armature of relay 311 in 'its left-hand position for a .predeterminedinterval of time.

How- Y Y icnn'ect .the .telegraphaequipment controlled @After a, predetermined interval of time ldependent upon, the constants ofthe windings and adjustments of relay 311, condenser 392, and theresistances-v associated therewith, the charg- -ing current owinggthrough the upper winding of relay 311 will `fall, to such a value that its eiect will'no longer overcome theeffect of the .currentnflowing throughthelower winding of this relay at which time thearmature of relay 31.1 is `operated to its right-hand position.

yAs set forth in the above-identified application of1BransonL et al., this predetermined interval of time comprisesa substantial proportion of the pause following the transmission-of .the-blank signal. l Y

If signals Vare received over the receiving lchannel.2i)2of -party.line 20| during this interval of time, the selector 30| in responding to thernwill cause,l the universal contacts UN to close. If; the signal received during this intime 1s other than a blank signal, a line feed signal or ha ligure signal, a circuit will be completed through the upper winding of relay 346 but no circuitwill be completed through the lower winding of this relay. Consequently, its armature vwill operate to its left-hand Vposition. If this -signal happens to be either the gure signal or ablank signal, circuits will operate as described in said aboVe-identied -applicationrof Branson et al.

The operation ofthe armature of relay 346 toits left-hand position completes a circuit for the operation of relay 319 from battery through the windingV of relay 319 and the center iset; of right-hand break contacts of relay 305' to ground through the left-hand contact, and

armature-of relay 346.V Relay 319 in operating interrupts the locking circuit of'relay 318 and permits this relay to release. At the end of the response of the selector 30| to the signal in yquestion the universalcontacts will open and interrupt the circuit-through the upper winding o f relay 346, whereupon this relay will be released and its armature moved to its righthand position, thus interrupting acircuit of relay 319 and permitting this Vrelay to release and restore the circuits to their previous condition. y 1

However, assuming that no signals are transmitted during ther charging time of condenser 39.2, the operation of relay 311 at the end of Vthe kpredetermined. timewinterval completes an ob- -viousfucircuit for `the operation Yof relay 380. fRelay 380 Y'invoperatin'g removes ground Yfrom y thegridof tube 310 and permitscondenser 312 to start to charge through high resistance 313. vThe operation of relay 38,0 also completes an obvious circuit for -the operation ofzrelay 38| `which relay operates and completes a circuit .for `lightingfthe' iilament kof vacuum tube 3.10. Tube ,3710.v does Y.not passanode urrentat this time due to the fact that the potentials applied to it are suchthat this tube will not passsufIlcientanode current to operate relay 31| for an appreciable interval ottime. f. The 'operation of relay' 38| interrupts the transmission circuit from the contacts of repeatings-.relay 3'82so thatany receiving equipment `connectedrto,then receiving @channel of party line r211| will not receivev the`V following signals transmitted thereover. dIt VVVshould ybe -noted thatthe lblank.signaltransmitted by the trans- ',mitter `rstart circuit while received by thereceivingequipment at anyof the stations which was then in the progressV of receiving a message will not be printed because the receiving equipment disregards this signal and does not respondto it by printing or'performing any other useful function at this time. v

If no further signals are received at the end of a predetermined interval of time, relay 31| is operated and an obvious circuit is completed for the operation of relay 319 which relay again restores the circuits to their previous conditions described above. y

However, if a line feed signal is received during this time interval and if no other signals are received preceding it, thev selector 30| in responding thereto will cause the LF contacts to momentarily close and complete a circuit for the operation of relay 342 from battery through the lower winding of. relay 346, winding of relay 342 and the left-hand inner operated contacts of relay 38| to ground to the momentarily closed contacts LF. The operation of relay 342 completes a'cirouit for. maintaining itselfv operated under control of relays 305 and 380. The operation of relay 3.42 again connects ground to the right-hand terminal of condenser 312 and thusV dischargesv this condenser and prevents the operation of relay 31| at this time. The operation of relay 342 completes an obvious circuit for the operation of relay 305. The operation of. relay 305 interrupts the locking circuit of relay 342 and permits this relay to release after the LF contacts open. The release of relay 342 removes ground from the righthand terminal of condenser 312. whereupon this condenser will again start to charge through the high resistance 313. However, relay 31| will not operate for an appreciable interval of" time as pointed cut above;

Assume now that the letter L signal has beenv transmitted by the transmitter start circuit SIG and received by the selector 30| during this interval of time. Selector 30| in responding to this signal will cause the L contacts to momentarily close and complete a circuit for the operation of relay 338 from battery through the lower winding of relay 346, the right-hand winding of relay 338 and left-hand operated contacts of relay 305 to Vground through the momentarily closed contacts L of selector 30|.

The operation of relay 338 completes an obvious circuit for lightinglamp 339, thus indicating that the transmitter controlled by station or equipment 3 |4 will -be connectedto transmit over the party line 20|. The operation of relay 338, in addition, connects the transmission channel 410 extending from the transmitter 44| at station 4|9 to the transmitting channel 203 of party line 20|. The operation of relay 338 also disconnects the transmission channel 203 extending to the secondary switching center 215 from the remainder of this channel. Consequently, any interfering currents encountered over that portion of transmitting channel will be ineffective to interfere with the transmission from transmitter YThe operation of relay 338 at this time also completes a locking circuitffor maintaining itself operated from battery through the break con' tacts of key 316 and relay 342, the left-hand winding and the left-hand inner operated contacts of relay 33B, the left-hand break contacts of relay 2 I1', winding of relay 2 6, the right-hand inner break contacts of relay 2|5, over conductor- 41| through the winding of relay 430 to ground through the tape control contacts 43|. If Hthe tape has been inserted in the transmitter 44|,

. quently, the locking circuit will be incomplete and relay 338 released when contacts L open.

However, assuming that tape has been vinserted inthe transmitter, the above-described circuit will be complete and maintain relay 338 operated and in addition cause relays 430 and 2|6 to operate. Relay 430 in operating completes a circuit through the start magnet 432 and c-auses the transmitter 44| to start the transmission of the message material stored in tape 433 over the conductors 41 and theY transmission channel 203 of party line 20| to the central exchange.

The operation of relay 2|6 in the circuit described above completes an obvious circuit for the operation of relay 2 I5.

Operation of relay 2|5 completes a circuit for lighting the filament 2 |0 and disconnects ground from the lower terminal of condenser 2|| which then starts to charge to a positive potential through high resistance 2|2. Relay 2|4 is not operated at this time because constants of tube 2|0, condenser 2li, and resistance 2|2 are such that it requires approximately thirty seconds after ground has been removed from the lower terminal of condenser 2|| before relay 2|4 operates. The operation of relay 2|5 interrupts the locking circuit through the left-hand Winding of relay 338 `extending over conductor 41|. The operation of relay 2|5, however, prior to the interruption of this locking circuit first connects ground to the left-hand winding terminal of relay 2|6 and thus tendsto maintain relays 2|0 and 333 operated. Relay 2|5 in `operating also connects battery through the winding of relay 2|*3 and the right-hand break contact of relay 2|1 `to conductor 41|, prior to interrupting this lead and thus maintains rel-ay 43|] operated.` Relay 2|3 operates due to current flowing through its winding in the above-described circuit and again connects the groundv from the vlower terminal of condenser 2| thus fully discharging the condenser and preventing the operation of Vrelay 2|4. Relay 430 is maintained operated at this time due to the battery connected through the l winding of relay 2|3 and the contacts of relays 2|1 and 2|5 to conductor 41|.

The circuits of the transmitter 44| are thus energized and the transmitter started into opera# y completes the circuit through the upper winding p of relay 311 and causes the armature of this relay to move to its left-hand positionwhere it interrupts the circuit of relay 380. Relay 380 in releasing connects ground to the right-hand terminal of condenser 312 andthus causes relay 31| to release. The release of relay 318 also interrupts the locking circuit of relay 319 which together with the release of relay 31| causes relay 319 'to release.

The release of relay 380 also.

causes relay 38| to release. YThe release of relay 38| interrupts the filament circuit of tube 310 and thus restores the circuits of this tube to their normal or idle condition. The release of relay 38| again establishes a transmission path from the contacts of the repeating relay 382 to any receiving instrument controlled from station 3|4 which may have previously been receiving messages.

Thereafter the circuits controlled by the secondary switching center 3 I4 remain in the abovedescribed condition so long as messages are transmitted from tape 433.' If in the meantime signals are transmitted over the receiving channel to party line 20|, addressed to any of the receiving stations served by this party line, the equipment and the circuits will operate as described in the above-identified application of Branson et al. but will not interfere with or aect the operation of the transmitting equipment 44| at station 4I9. i

The circuits or the other secondary switching centers operate in a similar manner in response to the transmitter start pattern assumed above to have been transmitted over the receiving channel of party line 20| except that the circuits controlled from these centers do not cause any transmitter controlled by these other secondary switching centers to start transmitting since they are selected by different selecting signals.

So long as tape 433 remains in the transmitter 44| in transmitting position, .contacts 43| remain closed and the circuits remain in the condition described above. However, when the end of tape 433 passes out of the transmitter 44|, after all of the signals recorded in it have been transmitted, contacts 43| open and interrupt the circuit of relay 430 and relay 2| 3. Relays 430 and 2 |3 release and relay 430 in. releasing interrupts the circuit of the start magnet 432 of transmitter 44| thus stopping the operation of transmitter 44| The release of relay 2I3 disconnects ground Thereafter the circuits will maintain in the above-described .condition so long as tape 433 remains in the transmitter 44|. If upon the completion of transmission of the signals in the second tape, a third tape is available for transmission, it may be similarly inserted within the thirty-second time interval after the second tape passes out of the transmitter and the message recorded in the third tape transmitted as described. This operation may be repeated as often as desired so long as each succeeding tape is inserted in the transmitter within the thirty-second time interval after the previous tape Passes out of the transmitter.

When the final tape 433 passes out of the transmitter 44|, contacts V43| will open and remain open for a longer interval of time than thirty seconds. Upon the opening of contacts 43| relays 430 and 2I3 will release. Relay 430 in releasing interrupts the circuit of the transmitter start magnet 432 which in turn releases and stops the operation of the transmitter 44 I The release of relay 2|3 removes ground from the lower terminal of condenser 2II which then starts to charge tov a positive potential through the high resistance 2|2. At the end of approximately thirty seconds during which relay 2| 3 does not reoperate, the potential of the lower terminal of condenser 2|I will reach a suicient positive value to cause tube 2 I0 to pass sufcient current for the operation of relay 2 I4. The operation of relay 2 I4 completes an obvious circuit for the operation of relay 2I'|. Relay 2I'| in operating interrupts the circuit of conductor 41| so that the subsequent insertion of the tape in transmitter 44| will not cause the reoperation of relay 430 and thus will not start the operation of transmitter 44 I Y The operation of relay 2|`| in addition interrupts the circuit through the winding of relay 2I6 and the left-hand locking winding of relay` y 338 thus permitting these relays to release. The

from the lower terminal of condenser 2|I which then starts to charge to a positive potential through a high resistance 2I2. However, as explained above, nothing further happens for at least approximately thirty seconds because relay 2I4 does not operate until after the lapse of this interval of Vtime in the specific embodiment of the invention described herein. In addition, incoming line circuit 622 and the transmitter start circuit 6I6 are arranged so that they will wait at least thirty, and preferably forty-five, seconds after the cessation of transmission of signals over the transmitting channel V203 of the party line-20| before initiating the transmission of another transmitter start pattern over the receiving channel 202 of the party line 20| by the transmitter start circuit 6 I 6.

If the attendant at station 4I9 has another length of perforated tape to insert in the transmitter at this time, it may be inserted and when inserted contacts 43| will again reclose'and complete the circuits for the operation of relays 430 and 2| 3 over conductor 41|. These relays will reoperate and relay 430 in reoperating again completes the circuit of transmitter start magnet 432 which magnet operates and causes the transmitter 44| to transmit the signals in accordance with the perforations in the tape 433 just inserted in the transmitter.

The operation of relay 2I3 again connects ground to the lower terminal of condenser 2I| thus discharging this condenser and preventing the operation of relay 2 I4.

release of relay 2|6 causes relay 2|5 to release, which vrelay interrupts the 'lament circuit of tube 2 0 and connects ground to the lower terminal of condenser 2|| thus causing lrelay 2I4 to release and relay 2I4 in turn causes relay 2I`| to release. Thus the. circuits at the secondary switching center 3|4 are restored to their normal or idle condition.r A short interval of time later, the incoming line circuit 622 will cause the transmitter start circuit 6 I 6 to either indicate that the transmission from station 4|9 has ceased or else will cause transmitter start circuit 6I6 to transmit another start pattern for testing another transmitter for material available for transmission over the transmitting channel 203 of the party line 20|.

If an end-of-transmission signal is perforated in tape 433, either before the tape passes out of the transmitter 44| or just before it passes out of the transmitter, the incoming line circuit 622 will recognize this signal and initiate the operation of the transmitter start circuit and cause it to transmit another start pattern. When the line feed signal of this start pattern is received, relay 342 will operate as described above. The operation of relay 342 at this time, which may be before the end of tape 433 passes out of transmitter 44| or before the end of the thirty-second time interval after the end of the tape passes Aout of the transmitter 44| as measured by condenser 2| I and tube 2|0, interrupts the circuit through the left-hand locking Winding of relay 338 and the winding of relay 2|| thus permitting these relays to release. The release of relay 2I6 causes relay 2 I 5 to release. Relay 2 I 5 in releasing disconnects battery through the winding of relay 2I3 from the conductor 4II extending to station 4 I 9. This causes relay 430 to release and stop the operation of the transmitter 44| at station 4I9. The release of relay 2I5 also interrupts the lament circuit of tube 2I0 and connects ground to the lower terminal of condenser 2 I I and thus restores the circuits to their idle condition.

The circuits operate in substantially the same manner when a transmitter stop pattern is transmitted over the receiving channel of the party line 20|. This signal causes the operation of the transmitter to be interrupted and the control circuits restored to their normal or idle condition in the manner described when another transmitter is started under control of the transmitter start circuit E I 6.

It is thus apparent that the circuits operate in substantially the same manner as those described in the above-identied application of Branson et al. excepting that the outlying operator has a period of approximately thirty seconds after one tape passes out of the transmitter before inserting another tape therein Without causing the transmitter in question to be disconnected from the transmitting channel and another transmitter started.

What is claimed is:

l. A telegraph system including a channel of transmission, a storage-type transmitter conditionable for transmissive association over said channel, means operated by absence of storage medium in said transmitter for interrupting the 35 transmissive relation of said transmitter to said channel, and means for delaying said interruption for a predetermined time during which the supply of further storage medium to the transmitter maintains the transmissive association.

2. A communication transmission channel, a storage-controlled transmitter for transmitting over said channel, remotely controlled apparatus local to said transmitter for operatively associating said transmitter with said channel when said transmitter is supplied with storage material available for transmission, other apparatus for interrupting said operative association when storage material is no longer available for transmission, and time delay equipment for delaying the operation of said last-mentioned apparatus for a predetermined time interval.

3. A communication transmission channel, a storage-controlled transmitter for transmitting over said channel, remotely controlled apparatus for operatively associating said transmitter with said channel When said transmitter is supplied with storage material available for transmission, other apparatus for interrupting said operative associationwhen the storage material passes out of said transmitter, time delay equipment for delaying the operation of said last-mentioned apparatus for a predetermined time interval and means responsive to the provision during said predetermined time interval of an additional supply of storage material available for transmission for restoring said time delay equipment.

4. In combination, a telegraph transmission channel, a tape-controlled telegraph transmitter, apparatus local to said transmitter controlled from a remote point vfor operativelyassociating said transmitter with said channel, apparatus controlled by the tape controlling said transmitter for interrupting said operative association, time measuring equipment for delaying the operation of said apparatus for interrupting said operative connection.

5. In combination, a telegraph transmission channel, a tape-controlled 4telegraph transmitter, apparatus responsive to the insertion of a tape in said transmitter for conditioning said transmitter for transmission, instrumentalities controlled from a point remote from said transmitter for operatively associating said transmitter with said channel when said transmitter is conditioned to transmit, time measuring apparatus for measuring a deiinite time interval and interrupting said operative connection at the end thereof, apparatus responsive to the passing of a tape out of said transmitter for initiating the operation of said time measuring apparatus, and equipment responsive to the insertion of another tape in said transmitter within said definite interval for restoring said time measuring apparatus Without interrupting said operative connection.

WALTER M. BACON. RITA SMITH KINKEAD, vA(imins11rtt1tar of the Estate of Fullerton S.

Kznlcead, Deceased. 

